Degasser attachment for internal combustion engines



Feb. 25, 1958 H. H. DIETRICH ET AL 2824726 DEGASSER ATTACHMENT FOR INTERNAL COMBUSTION ENGINES Filed Nov. 8, 1955 2 Shets-Sheet 1 I N V EN TOR5 JOHN M 5/! R 1a BYHOWAED H DmrE/ch' VI M01611.

ATTORNEY Feb. 25, 1958 H. H. DIETRICH ET AL DEGASSER ATTACHMENT FOR INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 2 Filed Nov. 8, l955 4TTOBNE Y INVENTORS JOHN M 5/1 2 1e BYHO WARD H D/ETEICH United States Patent 0 DEGASSER ATTACHMENT FDR INTERNAL COMBUSTIGN ENGINES Howard H. Dietrich, Berkley, Mich., and John M. Barr,

Rochester, N. Y., assignors to General Motors orporation, Detroit, Mich, a corporation of Delaware Application November 8, 1955, Serial No. 545,717

3 Claims. (Cl. 261-64) This invention pertains to internal combustion engines, and particularly to a degasser attachment for such engines.

It has long been recognized that during deceleration of a vehicle powered by an internal combustion engine, with the throttle valve closed and the engine driven by the vehicle, the idle-air fuel mixture supplied to the engine is not completely burned due to a lack of sufficient air. Under these conditions, the products of incomplete combustion, including free hydrocarbons, are discharged with the exhaust and expelled to atmosphere. ent invention relates to means for supplying a combustible mixture to the engine during periods of deceleration with a closed throttle valve and, thus, substantially eliminate the discharge of unburned fuel with the exhaust gases. Accordingly, among our objects are the provision of means for regulating manifold vacuum during engine deceleration; the further provision of means for admitting additional air directly into the intake manifold during deceleration when manifold vacuum is above a predetermined value; and the still further provision of means for mixing the additional air with fuel to produce a combustible air fuel mixture which is supplied to the engine during vehicle deceleration with a closed throttle.

The aforementioned and other objects are accomplished in the present invention by incorporating a manifold pressure regulator and auxiliary fuel supply system in an attachment for an internal combustion engine. Specifically, the internal combustion engine includes a conventional, plain tube downdraft carburetor for supplying air-fuel mixture to an intake manifold which distributes the combustible mixture to the several engine cylinders. The speed of engine operation is controlled by throttle valve means which regulate the quantity of combustible mixture supplied to the engine. When the throttle valve is open, fuel is supplied through the main carburetor jets, and when the throttle valve is closed, fuel is supplied through the idling jets.

During vehicle deceleration with a closed throttle valve, the vehicle drives the engine and creates an abnormally high manifold vacuum. Moreover, the quantity of air which flows around the closed throttle valve is insufficient to clean out the exhaust gases from the cylinders, and consequently the air-fuel mixture supplied by the idling system will not burn. Thus, it becomes necessary to supply additional air to purge the cylinders of exhaust gases. However, in order to form a combustible mixture having an air-fuel ratio of between 1214:1, additional fuelmust also be supplied.

The degasser attachment of this invention is supported on the carburetor and includes a cylindrical housing having open ends, the interior of the housing being subjected to manifold vacuum through a conduit. The upperend of the cylindrical housing is closed by a diaphragm which is clamped between the upper end of the housing and a cap member having an atmospheric vent therein. The lower end of the cylindrical housing has The pres-' attached thereto a stop member with a central aperture and an integral tube extending upwardly into the housing and forming a continuation of the central aperture. The tube constitutes a guide for a spring that normally urges the upper, or pilot diaphragm, against the upper cap. In addition, the upper end of the tube supports a pilot valve assembly capable of actuation by the pilot diaphragm so as to connect the interior of the tube with the interior of the housing.

A lower cap member is attached to the lower end of the housing, a second, or power diaphragm being disposed between the stop member and the lower cap. The lower cap member, likewise, has an atmospheric vent therein, a fuel chamber and a central outlet passage through which air-fuel mixture is supplied directly to" the intake manifold. The vacuum chamber formed between the power diaphragm and the stop member has a calibrated atmospheric vent therein which prevents the trapping of vacuum in this chamber when the pilot valve is closed. The power diaphragm carries a valve disc and is spring urged to a position wherein the valve disc closes the outlet passage which is connected to the intake manifold. The fuel chamber is connected by a conduit to a fuel pick-up tube disposed in the fuel reservoir, or float chamber, of the carburetor. Since the chamber between the power diaphragm and the cap member is normally at atmospheric pressure due to the disc valve being closed, no fuel will be picked up by the auxiliary fuel tube under normal running conditions inasmuch as the float chamber of the carburetor is also vented to atmosphere.

During normal running operation of the engine, the air-fuel mixture is controlled by the carburetor throttle valve. Likewise, during normal idle operation of the engine, the fuel is supplied to the idling ports and mixed with the air passing around the periphery of the closed throttle valve. However, during deceleration of the engine with a closed throttle when the vehicle is driving the engine, the manifold vacuum increases appreciably above the manifold vacuum created during all normal running operation of the engine. When the manifold vacuum reaches a predetermined value, the pressure differential on opposite sides of the pilot diaphragm will be sulficient to overcome the restraining force of the spring and the pilot valve diaphragm will move downwardly to open the pilot valve. Upon opening of the pilot valve, the vacuum chamber of the lower diaphragm motor will be subjected to manifold vacuum, and the pressure differential on opposite sides of this diaphragm will effect movement of the diaphragm so as to open the outlet passage in the lower cap. When the outlet passage is open, the air flowing across the fuel passage creates a suction effect which causes a flow of fuel from the fuel reservoir and into the air stream which is being supplied to the intake manifold. Thus, the additional air is mixed with fuel, and the resulting air fuel mixture supplied from the idling jets and the air flow around the closed throttle valve plus the additional air and fuel supplied by the degasser attachment, is combustible.

The degasser attachment operates intermittently during deceleration with a closed throttle, since as soon as the outlet passage is opened, the manifold vacuum decreases, and as soon as the outlet passage is closed, the manifold vacuum immediately increases. The intermittent operation of the degasser attachment operates to regulate mani-' fold vacuum during deceleration in addition to supplying additional air and fuel so as to produce a combustible airfuel mixture. In this manner, the discharge of free hydrocarbons with the exhaust from the engine during deceleration is eliminated.

Further objects and advantages of the present invention will be apparent from the following description, reference ferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a fragmentary view, partly in section and partly in elevation, of a carburetor and intake manifold assembly having the degasser attachment of this invention.

Fig. 2 is a top view, in elevation, of the degasser attachment.

Fig. 3 is a sectional view taken along line 3 --3 of Fig. 2.

F Fig. 4 is a sectional view taken along line 4--4 of Fig. 5 is an enlarged fragmentary sectional view taken along line 55 of Fig. 4.

Fig. 6 is a sectional view taken along line 66 of Fig. 3.

Heretofore, it has been proposed to eliminate the discharge of unburned fuel with the exhaust gases during deceleration of a vehicle with a closed throttle, by admitting additional air either directly to the intake manifold or through the throttle valve by means of vacuum actuated poppet valves. to present a solution to the problem by leaning out the air fuel mixture supplied to and purging exhaust gases from the cylinders during deceleration, no means have been devised to control the supply of additional air so that the air-fuel mixture supplied to the cylinders is combustible. In other words, no one has been able to devise a device which will operate on all vehicle engines to prevent the discharge of unburned fuel with the exhaust during deceleration by merely admitting additional air to the intake manifold, since in some cases, the resultant air fuel mixture is too lean to be ignited in the cylinders, and in other instances the exhaust gases will not be sufficiently cleaned out of the cylinder combustion chambers to permit combustion of the mixture supplied. The present invention presents a satisfactory solution to the problem of degassing and operates satisfactorily on all engines since the additional air supplied during deceleration is mixed with fuel. The amount of fuel which must be added to the additional air to result in a completely combustible mixture being supplied to the engine during deceleration can be accurately calibrated. Thus, the amount of fuel supplied by the idling jets with a closed throttle can be accurately determined. Moreover, the amount of air flowing around the closed throttle valve can also be determined. With this information, it is a relatively simple matter to calibrate the additional fuel and air supplying system so as to supply a mixture withing the combustible portion range to the engine.

With particular reference to Fig. l, the degasser attachment is indicated generally by the numeral 10, the degasser attachment 10 being connected to a carburetor 11 by means of a pipe coupling 12. The pipe coupling 12 actually communicates with the throttle body 13 of the carburetor, the throttle body 13 having a sidewall opening 14 communicating with the pipe 12. By way of illustration, the carburetor 11 is of the dual barrel type and, thus, includes two induction passages 15 and 16, the induction passages having butterfly type throttle valves 17 and 18 therein. The throttle valves 17 and 18 are attached to a common throttle actuating shaft 19, which is connected by conventional linkage means, not shown, so as to be operated by the accelerator pedal, not shown, of the vehicle. It should be noted that the sidewall opening 14 in the throttle body 13 communicates with the induction passage 16 posterior to the throttle valve 18. Moreover, in accordance with conventional practice, the two induction passages 15 and 16 are interconnected by a cross-over passage 20.

In accordance with conventional practice, each induction passage is supplied with fuel through a main nozzle, not shown. When the throttle valves 17 and 18 are in the closed position, as depicted in Fig. l, the idle-air fuel While this arrangement appears emulsion is supplied through idling ports 21 and 22, respectively, located in the throttle body 13 posterior to the throttle valves. Air-fuel emulsion is drawn through the ports 21 and 22 from an idle well in the carburetor, not shown, due to the manifold vacuum existent in the induction passages 15 and 16 posterior to the throttle valves.

Induction passage 15 is connected to an engine intake manifold pipe 23, while induction passage 16 is connected to intake manifold pipe 24, as is conventional in the V-S type engines. The two manifold pipes 23 and 24 are, likewise, interconnected by the cross-over 20 in the throttle body 13 so that the same absolute pressure exists in both manifold pipes 23 and 24 at all times.

With particular reference to Figs. 2 through 6, the structural details of the degasser attachment will be described. The degasser attachment 10 comprises a cylindrical housing 25 having open ends. As seen particularly in Fig. 4, the housing 25 has a threaded sidewall opening 26, which, as depicted in Fig. 1, receives a coupling 27, the coupling 27 being connected to a conduit 28, which communicates with the intake manifold pipe 24 through a coupling 29. The upper end of the housing 25 is closed by a cap member 30, a suitable diaphragm 31 being interposed between the cap member 30 and the upper end of the housing 25. The cap member 30 is attached to the housing 25 by a plurality of bolts 32. The diaphragm 31 has attached thereto by means of a rivet 33, a head assembly 34. The cap 30 is formed with a central aperture 35 constituting an atmospheric vent for the chamber 36 formed between the upper surface of the diaphragm 31 and the inner surface of the cap 30.

The lower end of the housing 25 has attached thereto a stop member 37, a diaphragm ring 38, and a lower cap 39, these parts being maintained in assembled relation with the housing 25 by a plurality of bolts 40. The stop member 37 includes an upwardly extending tubular member 41, which communicates with a central aperture 42 in the stop member. An adjustable spring seat 43 is disposed within the housing 25 between the stop member 37 and the diaphragm 31, the spring seat having a central aperture 44 through which a tubular projection 41 extends. The spring seat 43 is maintained in assembled relation with the housing 25 by means of a pair of bolts 45 supported on the cap member 30 and having threaded connection with the seat 43. One end of a coiled compression spring 46 engages the seat 43, the spring 46 encircling the tubular projection 41, which acts as a spring guide therefor, The other end of the spring 46. engages a spring seat 47, which is received by the lower disc of the disc assembly 34 attached to the center of the diaphragm 31. The spring 46 normally maintains the diaphragm 31 in a position where the disc assembly 34 abuts the cover 30, as depicted in Fig. 3 A pilot valve assembly generally depicted by the numeral 48 is supported by the upper end of the tubular projection 41. The pilot valve assembly 48 comprises a valve cage 49, which is snugly received in the tubular projection 41, the valve cage having an internal shoulder 50 and a plurality of ports 51, which interconnect the interior of the valve cage and the chamber 52 of the housing 25. A valve element 53 is disposed within the valve cage and urged upwardly by a spring 54 so that the valve norrnally closes the open end of the cage 49. The spring 54 reacts between the valve cage shoulder 50 an d a seat 55 on the valve stem. When the chamber 52 is subjected to vacuum of a predetermined magnitude through the opening 26, the pressure differential acting on opposite sides of the diaphragm 31 will be sufiicient to overcome the resisting force of the calibrated spring 46 and, hence, the diaphragm will move downwardly,'as viewed in Fig. 3, to a position where the rivet 33 engages the upper end of the stem of the valve 53 so as to open the valve and interconnect the interior of tubular projection 41 with the chamber 52. Thus, the upper diaphragm; 31 is termed the pilot diaphragm.

The tubular projection 41 communicates through the central aperture 42 in the stop member 37 with a vacuum chamber 56 for a power diaphragm 57, which is flange mounted between the ring 38 and the cap member 39. The diaphragm 57, likewise, has attached thereto a disc assembly 58 by means of a rivet 59, the lower surface .of rivet 59 constituting a valve 60. The valve 60 normally closes a centrally disposed outlet passage 61 in the lower cap member 39 by engaging an internal shoulder 62 circumscribing the passage 61. The diaphragm 57 is normally maintained in position where the valve 60 closes the passage 61 by a coiled compression spring 63, opposite ends of which engage the diaphragm disc assembly 58 and the stop member 37.

As seen particularly in Figs. 3 and 6, the lower cap member 39 forms a chamber 64 with the diaphragm 57, which is connected to atmosphere through an opening 65. In addition, the annular shoulder 62 is radially spaced from a second annular shoulder 66 concentric with the shoulder 62 by an annular groove 67. The annular groove 67 communicates with a fuel conduit 68 through a passage 69. The fuel conduit 68 is connected by a union coupling assembly 70 to a conduit 71, as seen in Fig. 1. The conduit 71 communicates with afitting 72 mounted on the carburetor 11. The fitting 72 is T-shaped and has attached thereto a calibrated air bleed 73 and an inlet fuel tube 74 which projects through the carburetor housing and into the fuel reservoir, or float chamber 75. The tube 74 is open at the lower end, the lower end always being submerged within the fuel of the reservoir 75. In addition, the tube 74 is formed with a calibrated restriction 76 adjacent the lower end thereof. The tube 74 is connected to the fitting 72 by a coupling 77 and is maintained in fixed relation relative to the carburetor by a nut '78. Fuel cannot leak, or siphon, from the fuel reservoir 75 through the tubes 71 and 68 when the valve 60 is closed since opposite ends of the tubes are at atmospheric pressure.

With particular reference to Figs. 3 through 5, the stop member 37 has formed therein a radially extending bore 79, which interconnects the chamber 56 with atmosphere through a calibrated bleed screw 80. The calibrated air bleed for the chamber 56 prevents the trapping of vacuum in chamber 56 when the pilot valve 53 closes so that the diaphragm 57 will respond quickly and in a follow-up manner to the movements of the pilot diaphragm 31. In other words, the chamber 56 is bled to atmosphere through the screw 80 so that unless the pilot valve 53 is open,

the spring 63 will be operative to move the diaphragm 57 downwardly, as viewed in Fig. 3, and thereby position the valve 60 to close the outlet passage 61.

Operation During normal running operation of an engine equipped with a degasser attachment of this invention, fuel is supplied through either the main or idling jets of the carburetor in a conventional manner. Moreover, the air to fuel ratio during normal running operation is not in any way affected by the degasser attachment disclosed herein. However, during deceleration of the engine under conditions where the vehicle drives the engine, the intake manifold vacuum reaches an abnormally high value. In some cases manifold vacuum may reach a value as high as 26" of mercury. The resisting spring load on the pilot diaphragm 31 is adjusted so that this diaphragm is not actuated until manifold vacuum exceeds a value which is created during normal running operation, for instance, 23". When the manifold vacuum reaches a value of 23", the pilot valve diaphragm 31 will move downwardly due to the pressure differential on opposite sides thereof and the rivet 33 will open the pilot valve 53. When the pilot valve 53 is open, manifold vacuum existent in chamber 52 of the housing is communicated to chamber 56. When the chamber 56 is subjected to manifold vacuum even of a relatively low value, the diaphragm 57 will 6 move upwardly so as to displace valve 60 and open passage 61 to the chamber 64, which is connected to atmosphere. Thus, air will flow across the annular groove, or fuel chamber, 67 between shoulders 62 and 66 and into the outlet passage 61, which is connected by pipe 12 to the intake manifolds 23 and 24 through the throttle body 13. Air flowing across the annular groove 67 creates an aspirating effect due to its high velocity so as to result in fuel being drawn from the reservoir 75 through the tube 74 and conduits 71 and 68 to passage 69 in the annular groove 67. The fuel in annular groove 67 is mixed Withair flowing thereacross to form an air-fuel emulsion which is supplied directly to the intake manifold of the engine. The air fuel mixture supplied by the degasser attachment mixes with the idle air fuel mixture supplied by the carburetor idle fuel supply system and forms a combustible mixture which is distributed by the intake manifold pipes 23 and 24 to the several engine cylinders and purges the exhaust gases therefrom. In this manner, the discharge of unburned fuel with the exhaust gases during deceleration is eliminated.

The degasser attachment operates intermittently during deceleration with closed throttle valves, since as soon as the manifold vacuum decreases below 23", the pilot valve diaphragm 31 moves upwardly and the pilot valve 53 closes. When this occurs, the chamber 56 quickly reaches an absolute pressure by reason of bleed screw 80, which enables the spring 63 to move the diaphragm 57 downwardly so that valve 60 closes the outlet passage 61. Thus, during vehicle deceleration with a closed throttle, the diaphragms 31 and 57 are intermittently actuated so as to maintain manifold vacuum substantially constant at 23". As soon as the speed of the engine reduces to a value wherein a manifold vacuum of 23" is not created, the degasser attachment is completely cut off.

From the aforegoing, it is apparent that the present invention provides a degasser attachment for internal combustion engines wherein the fuel and air supply is augmented during deceleration soas to produce a cornbustible mixture. Moreover, the degasser attachment does not in any way aifect the normal running operation of the engine, and there will be no hesitation in engine operation after degassing since the carburetor idle fuel supply is not cut off during degassing.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A degasser attachment for an internal combustion engine having an intake manifold and a carburetor, including, a housing assembly having a chamber subjected to manifold vacuum and an outlet passage operatively connected to said intake manifold, first motor means in said housing assembly, second motor means in said housing assembly, a pilot valve in said housing assembly capable of actuation by said first motor means when the manifold vacuum in said chamber exceeds a predetermined value during engine deceleration to subject said second motor means to manifold vacuum, a valve for closing said outlet passage or opening said outlet passage to atmosphere and operatively connected to said second motor means, and fuel passage means located adjacent said outlet passage for supplying fuel to the air admitted to the intake manifold through said outlet passage when said valve is open.

2. A degasser attachment for an internal combustion engine having an intake manifold and a carburetor, including, a housing having a chamber subjected to manifold vacuum, means connected to said housing so as to form a second chamber, a pilot valve within said housing for interconnecting said first and second chambers, first motor means in said housing and responsive to manifold vacuum in excess of a predetermined value during engine deceleration for opening said pilot valve to subject the second chamber to manifold vacuum, a member at: tached to said houing and having an outlet passage operatively connected to said intake manifold, a valve for closing said outlet passage or opening said outlet passage to atmosphere, second motor means responsive to vacuum in said second chamber for opening said valve when said second chamber is subjected to manifold vacuum, a fuel chamber in said member adjacent said outlet passage, and means for supplying fuel to said chamber so that said fuel will be mixed with the air flowing through said outlet passage to said intake manifold when said valve is open.

3. The degasser attachment set forth in claim 2 Wherein said second chamber includes a calibrated bleed, to

atmosphere to prevent the trapping of manifold vacuum therein when the pilot valve is closed.

References Cited in the file of this patent UNITED STATES PATENTS 1,735,633 Bragg et a1. Nov. 12, 1929 1,946,284 Huber Feb. 6, 1934 2,094,555 Von Hilvety Sept. 28, 1937 2,212,936 Hoof Aug. 27, 1940 2,621,911 Lindsteadt Dec. 16, 1952 FOREIGN PATENTS 405,346 Great Britain Feb. 8, 1934 

